There are several types of dashes in the English. There's the hyphen ( - ), the en dash ( – ) and the em dash ( — ). What's the difference?
The hyphen is the most common dash. Technically, it's not a dash, it's a hyphen, for there is a 'family' of dashes and the hyphen isn't one of them. But for most people, the hyphen is also called a dash. Most people know where and when to use a hyphen. You use it to connect two words to make it into an adjective. You use it to break up a word that is running to the end of the line and you want to write half on the top line and the rest on the next line. You break up the said word at a the end of a syllable and use a hyphen to indicate the rest of the word is on the next line.
What about the en dash? The en dash is so called because traditionally, the width of the dash was the approximately the width of the letter n. The most common use of the en dash is used to indicate a range of numbers like "6–8 years of planning". The en dash can be used for other sets of numbers like date and time. This is easy enough to write on paper, but gets trickier to do with software. Most people simply substitute a hyphen when indicating a range of numbers. If you're picky, on Microsoft Office Word, you can select the Insert menu, then select "Symbol", then select "Special chacters" then pick out the en dash. You can also learn the keyboard shortcut indicated inside this menu and use that the next time.
The em dash is—you guessed it—the width of the letter m. It is used to indicate an interruption in the middle of a sentence (like in the previous sentence) or used to indicate that a sentence has been interrputed and did not end.
For example: I did not say that you could—
Notice that there is no other punctuation mark and that there is no space between could and the em dash. Also, notice that when the em dash is used in a pair for a parenthetical interruption in a sentence, there are no spaces before or after the em dashes. This actually, makes for an interesting auto shortcut in Microsoft Word. To insert an em dash into your sentence, simply type a word, then without inserting any space type two consective hyphens, then the next word and then finally add a space and you will see Word convert the two hyphens into em dashes.
For example type this: is--you guessed
And Word will convert it to the following when you hit the spacebar after the letter u: is—you guessed
Isn't that a neat trick?
